Semantic Web-Based Information Systems: State-of-the-Art ...
Semantic Web-Based Information Systems: State-of-the-Art ...
Semantic Web-Based Information Systems: State-of-the-Art ...
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Query ng <strong>the</strong> <strong>Web</strong> Recons dered<br />
Three Syntaxes: XML, Compact Human-Readable, and Visual<br />
While it is desirable that a query language for <strong>the</strong> (conventional and/or <strong>Semantic</strong>)<br />
<strong>Web</strong> has an XML syntax, because it makes it easier to exchange query programs<br />
on <strong>the</strong> <strong>Web</strong> and to manipulate <strong>the</strong>m using <strong>the</strong> query language, a second, more compact<br />
syntax easier for humans to read and write is desirable. Therefore, two textual<br />
syntaxes should be provided: a purely term-oriented XML syntax and ano<strong>the</strong>r one<br />
that combines term expressions with non-term expressions like most programming<br />
languages. This o<strong>the</strong>r syntax should be more compact than <strong>the</strong> XML syntax and<br />
better readable for human beings. Both syntaxes should be interchangeable (<strong>the</strong><br />
translation being a low cost process).<br />
Third, a visual syntax can greatly increase <strong>the</strong> accessibility <strong>of</strong> <strong>the</strong> language, in particular<br />
for non-experts. This visual syntax should be a mere rendering <strong>of</strong> <strong>the</strong> textual<br />
language, a novel approach to developing a visual language with several advantages.<br />
It results in a visual language tightly connected to <strong>the</strong> textual language; namely, it<br />
is a rendering <strong>of</strong> <strong>the</strong> textual language. This tight connection makes it possible to<br />
use both <strong>the</strong> visual and <strong>the</strong> textual language in <strong>the</strong> development <strong>of</strong> applications.<br />
Last, but not least, a visual query language conceived as a hypertext application is<br />
especially accessible for <strong>Web</strong> and <strong>Semantic</strong> <strong>Web</strong> application developers.<br />
Modeling, Verbalizing, and Visualizing<br />
• Authoring.and.modeling:.Authoring correct and consistent queries <strong>of</strong>ten<br />
requires considerable effort from <strong>the</strong> query programmer. Therefore, semiautomated<br />
or fully automated tool support both for authoring and for reading<br />
and understanding queries is essential.<br />
• Verbalization:.For verbalizing queries, as well as <strong>the</strong>ir input and output, some<br />
form <strong>of</strong> controlled natural language processing is promising and can provide<br />
an interface to <strong>the</strong> query language for untrained users. The importance <strong>of</strong> such<br />
a seemingly free-form “natural” interface for <strong>the</strong> <strong>Web</strong> is demonstrated by <strong>the</strong><br />
widespread success <strong>of</strong> <strong>Web</strong> search engines.<br />
• Visualization:.As already discussed, a visualization based on styling <strong>of</strong> queries<br />
is highly advantageous in a <strong>Semantic</strong> <strong>Web</strong> setting. As demonstrated in Berger<br />
et al. (2003], it also can serve as a foundation for interactive features such as<br />
authoring <strong>of</strong> queries. On this foundation, more advanced authoring tools (e.g.,<br />
for verification and validation <strong>of</strong> queries) can be implemented.<br />
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